textproduct: Rapid City

KEY MESSAGES

- Rain and snow showers continue through Monday afternoon, heaviest precipitation favored across south-central South Dakota.

- Cooler, unsettled weather continues through next week, with a gradual warming trend towards the end of the week.

UPDATE

Issued at 927 PM MDT Sun Apr 26 2026

Large upper trough over the western two thirds of the CONUS will continue to bring cool and unsettled weather to the region for the first half of this week. KUDX radar shows light precip across most of the forecast area. Most of this is falling as rain/drizzle, but surface obs and webcams show snow falling over the Black Hills and portions of the NE WY plains behind a cold front pushing through. As the previous forecast has mentioned, precip will pick up after 06z tonight. Rain will mix with or change to snow across the western SD plains. Snow will continue across the Black Hills into the NE WY plains, with totals under 3 inches. Precip will wind down through the morning hours tomorrow. QPF totals for tonight and Monday will generally be in the 0.15-0.35" range...perhaps slightly higher across SCentral SD. The next wave rounding the base of the trough is expected to bring additional light precip to the area on Tuesday, but the higher QPF will stay south of the CWA.

DISCUSSION

(This Evening Through Sunday) Issued at 1234 PM MDT Sun Apr 26 2026

Current upper-air analysis and water vapor imagery depict the lingering upper low over central SK/MB, with multiple shortwaves embedded southwest of the low and a second low positioned over UT/CO. WV imagery indicates increasing low-level cloud cover moving in from NE/WY, along with expanding rain and snow showers over portions of southwest and central SD (per regional radar loop and webcams). Current surface observations show temperatures in the 30s and 40s with east/southeast winds, gusting to 20 to 30 mph.

The upper low over central Canada begins to shift northeast this afternoon/evening, allowing the second surface-low to move off the Rockies and into the Great Plains. This second low will be the driving factor for the location and duration of precipitation for today and into Monday across the CWA. Current model runs place the low over CO, progressing northeast through Sunday and Monday before exiting the region Monday night. Current ensemble guidance suggests rain and snow will occur on and off through the remainder of today and into Monday morning, with the heaviest precip rates between 18Z and 00Z this afternoon and again between 06Z and 12Z Monday. Some uncertainty remains regarding exact QPF totals due to disagreement between ensembles/models (e.g. NBM, HREF, ECMWF). Even with this uncertainty, the highest QPF amounts are still expected over south- central SD, where at least 0.75" of liquid remains possible (65 to 75% chance, NBM-CONUS). Southwestern SD and the Black Hills may still receive at least 0.5" of liquid (55 to 75% chance, NBM-CONUS), with lower amounts over northwester SD and northeastern WY. Higher elevations of the Black Hills may receive 1 to 3 inches of snow, while 1 to 2 inches are possible across portions of northeast WY through Monday morning. As the pressure gradient strengthens on the back side of the surface-low Monday afternoon, gusty northerly winds (35 to 45 mph) will develop over the SD plains east of the Black Hills.

As the surface-low departs, drier but still unsettled conditions are expected through the rest of the week. Another disturbance will move through late Monday night into Tuesday, increasing precipitation chances. Near-average temperatures are expected the rest of the week, with highs mainly in the 50s and 60s after Monday.

AVIATION

(For the 06Z TAFS Through 06Z Monday Night) Issued At 1039 PM MDT Sun Apr 26 2026

VERY moist conditions throughout the entire surface, to lower, to middle atmospheric column continue tonight, with widespread (generally light) rain and snow, BR and even FG, and thick clouds as low as 300-700 feet. We really have no confidence in conditions improving above LIFR to IFR territory until precip breaks up/diminishes midday Monday as the supporting/parent shortwave trough pulls east of the region. We have nudged this improvement about an hour earlier than the previous forecast...now around 17z/11am at KGCC and 19z/1pm at KRAP, at which time vsbys should improve given an end to steady precip and cigs may lift to MVFR. SOME of the CAMs, as well as the 00z HRRR, seem to hint at some slight/uncertain improvement possibly occurring at KRAP as early as 15z/9am (if precip lightens/starts to break up, perhaps the start of a slow improving trend), so have captured that in the latest TAF as well, but this is low confidence. Expect breezy northwest winds until sunset or so Monday evening. Quite a bit of low-level moisture will linger overnight Monday night along with winds becoming light...so far guidance favors continued low clouds (at least MVFR) over fog, but hard to rule either out.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.